* Adds safety checks to scripting orders with waypoints
Turns out setting a waypoint order then trying to get to target of that order in the same frame triggers a crash in the scripting API for ship orders (`order.cpp` line 295). This was due to invalid lookups which lacked safety checks.
This PR adds those safety checks. Now, if this situation is encountered, it leaves `objnum` at -1 and thus returns an object for which `isValid` is false.
Fix is tested and works as expected. Also fixes#5172
* appease clang
* cleanup thanks to Goober
* clang again
* forgot to re-add the nullptr
* remove redundant checks
When iterating through `Ship_obj_list`, check the `Should_be_dead` flag before using the object. This fixes#4990 and adds defense-in-depth checks to guard against similar errors elsewhere.
I considered moving the `Ship_obj_list` removal from `obj_delete` to `ship_cleanup`, but decided it would be prudent to avoid fundamental changes to lifecycle management.
When iterating through various object collections, check for the should-be-dead flag to avoid returning objects that are on the verge of being deleted.
Separately, this adds the `isExpiring` function to check for should-be-dead objects.
This PR also makes object iteration consistent across all object types, both to reduce code duplication and to ensure that the length and iteration are done using the same algorithm. Furthermore, if the number of should-be-dead objects is nonzero, the Lua array count for that frame will be different from the internal array count for that frame.
Fixes#5034.
Allow `mn.sendMessage` to send from a ship source, not only a string source, by allowing the ship object to be specified as the first argument. Also add `ship:sendMessage` which is a more streamlined version of the same thing.
Adds gravity! Applies on a per-mission basis, and weapons, ships, debris, and asteroids now have a configurable "gravity const" which multiplies the effect of gravity on them, by default everything except debris is 0 (meaning no effect even when the mission has gravity). AI and the lead indicator will also lead for ballistic trajectories as well, given a gravity-affected weapon. No FRED support or gravity direction control yet, to come in later PRs.
We shouldn't be checking that the `cci_h` is valid by seeing if it is greater than -1 because by that point it never will be. Instead, we should be checking that the incoming id is valid and setting to the invalid state if it is not.
Load campaigns using the full path provided by the user, not just from the configured mod paths.
Also tweaks initialization based on the campaign having already been cleared in `mission_campaign_clear()`.
This is a new Lua API function that allows creation of arbitrary debris pieces, whether chunks of a ship's hull or shards of shrapnel. All of the parameters are optional, and a wide variety of situations are possible ranging from vaporized bits to static chunks to chunks propelled by an explosion.
* Add access to damage type, swarm, and corkscrew data
* Also return if the weapons have the appropriate flags
* Return nil for invalid handle and clarify documentation
Goober5000